Surface broach



Dec. 114, 1945. .J. A.`MARKSTRUM SURFACE BROACH 2 Sheets-Shee't 1 Filed June 26, 1942 n n x n L Ll l/l l I l Dec. 11, 1945. J. A. MARKSTRUM SURFACE BROACH 'Filed June 26, 1942 2 rsheets-sheet 2 Patented Dec. 11, 1945 SURFACE BROACH John A. Markstrum, Detroit, Mich., assignor to Ex-Cell-O Corporation, Detroit, Mich., a corporation of Michigan Application June 26, 194,2, Serial No. 448,597

11 Claims. ('Cl. 29-95.1)

The present invention relates to vimprovements in surface broaches and has particular reference to a broach adapted to take a progressive cut laterally across a work surface.

One of the objects of the present invention is to provide a novel surface broach comprising a plurality of similar broach sections adapted to be removably secured as inserts to a slidable support.

Another object is to provide a new and improved surface broach of the sectional type in which spaced sections are arranged to cut in opposed relation from opposite sides toward the center of the work surface.

A further object is to provide a novel surface broach comprising a slidable support, and a broach section adapted to be removably secured thereto in initial and reversed positions so that when one longitudinal side is dull, the section may be reversed to locate the other longitudinal side in cutting position, thereby doubling the cutting life of the section.

A general object of the invention is to provide a novel surface broach which is simple in construction, and economical to set up and maintain.

Other -objects and advantages will become apparent as the description proceeds.

In the accompanying drawings,

Figure 1 is a plan view of a breach embodying the features of my invention.

Fig. 2 is an end view of the broach shown in operative relation to a work part.

Fig. 3 is a fragmentary perspective View of one of the broach sections.

Fig. 4 is a plan view of a modified form of broach.

Fig. 5 is an end View of the broach shown in Fig. 4.

Fig. 6 is a fragmentary sectional View taken substantially along lines G-S of Fig. 4.

Referring more particularly to the drawings, the broach comprises a slidable support 1 of rectangular form adapted to be connected to the ram (not shown) of the broaching machine for longitudinal movement from left to right in Fig. 1. A plurality of identical broach sections 8 (Fig. 3) are removably mounted as inserts on the support 'I in predetermined arrangement, depending on the requirements of the broaching operation to be performed. In the present instance, each of 'the broach sections 8 consists of a rectangular bar having at parallel side surfaces 9 and IU, and 'a flat bottom surface II. The top surface lof the section 8 is formed with a longitudinal series of suitably relieved broach teeth I 2 separated from each other by clearance spaces I3, and extending crosswisevof the section. More particularly, each tooth I2 has a top edge I4, and is chamfered at opposite ends to provide oppositely inclined side cutting edges I5 and I5. The successive teeth I2 are arranged to take a progressive series of parallel cuts. In the present instance, the cutting offset is obtained by inclining the broach section 8 at a suitable angle to the direction of movement of the support 1 in the broaching operation. Consequently, the teeth I2 can be made, and preferably are made, of uniform height and width, and with a uniform and symmetrical cutting contour. By lat erally inclining or orientating the breach section 8 to the plane of the support 'I at the angle of the chamfer on the ends of the teeth 12, one series or the other of the side cutting edges 'I5 and I6 is disposed in cutting position. If, for example, the cutting edges l5 are disposedv in cutting position, lateral reversal of the angularity of the breach section 8 will dispose the cutting edges I6 uppermost in position to cut the work.

The broach sections 8 may be selected and ar ranged to provide different forms of composite broaches. Ein Figs. 1 to 3, four series of breach sections are provided and are arranged in pairs of opposed sections to vout from opposite sides toward the center of 'two surfaces S on a snorkpiece W, the plane of cut being indicated by the dotted line I1. l

The broach sections 8 may be mounted yon the support 1 in any suitable manner to present the cutting edges to the work. In the prese-nt instance, the support 1 is formed in the top surface with four longitudinal grooves I8,A I9., 20 and 2| of angular form. The two outermost grooves I8 and I2| converge toward each other from the leading to the trailing end of 'thesupport 1. lThe two innermost grooves I9 and 23 diverge from each other 'and converge with the respective outermost grooves from the leading toward the trailing end of the support, and are somewhat shorter than the outermost grooves to provide an overlap.

Each of the grooves I3 to 21 is suitably shaped to support Athe broach sections 8 in a tilted cutting position with one vset or the other of the side edges I5 and 'I6 disposed uppermost and parallel to the top surface of the supporting slab 8. In the present instance., each groove lis V-shaped, with sides 22 and 23 extending 'at right angles to each other, and laterally orion inclinatienef'the sections 8 previdesthe Ylateral cutting offset of the successive teeth I2 of each series, and the number of sections provided in each series is dependent on the desired width of out within the limits of the ram stroke. In the present instance, three sections 8 are disposed in each of the outermost grooves I8 and 2 I', and two sections are disposed in the innermostl grooves I 9 and 28. The sections in the groevesI and I9, and also those in the grooves 20 and 2 I, are tilted oppositely and suitably spaced to cut from opposite sides toward the center across the respective work surfaces S. The trailing section of each outer series of sections overlaps the range of out Yef the associated inner series ef sections, and hence serves te remove the narrow fin or rib of stock which remains after the oppositely disposed sections have completed their cuts.

' A conventional type of surface breach section 25 in the ferm of a slab may be mounted on the trailing end of the support 'Iy te produce the nal size and finish on the werk W. The breach section 25 has a series of transverse cutting edges 26 which are of progressively increasing height from the leading to the trailing end of the slab, and is of such width that it extends across the aggregate krange of the preceding series of vbreach sections 8.A e e Y I n operation, and referring Vparticularly to Figs. 1 and 2, the support I is translated longitudinally along the work W te be breached. VInitially, the pairs of opposed leading breach sections I8 and I3, and 2G and 2|, start the breaching cut from opposite side edges toward Ythe center of .the respective surfaces S valong thel In the continued translation ofthe l plane Il. support I the intermediate pairs ef opposed breach sections ISand I9, and 28 and 2I con-V .tinue the breachingcut, and leave only a narrow iin er rib of stock at each of the spaces 21. 'Ihe third er trailing sections I8 and 22 then serve to remove the final stock to complete the cut across the werkv W. When provided, the conventional breach section 25 serves te take a finish cut en the surfaces S.

It will be evident that all of the'broaching sections 8 are alike in ferm, and adapted for interchangeable use. They may be selected and arranged te provide composite breaches of different ferms depending on the requirements of the werk. They are interchangeable from one groeve te another so as te cut from one side er the other of the werk, and as a result, one series ef side cutting edges I may be used until dulled, and'then the other series of cutting edges I6 may be used. As a consequence, the cutting life of each breach section is doubled, and in general the composite breach is economical te set up and to maintain.

The ferm of breach illustrated in Figs. 1 te 3 f is especially adapted for breaching work surfaces S of comparatively narrow width which can be breached within the available stroke of the support I merely by two cuts starting at opposite side edges of the surface. When the work surface, such as vthe surfaceSi Vof the werk W1 of Fig. 5, is `so wide that, within the available stroke of the support, two cuts respectively from opposite sides are, insuicient te breach the entire surface, the breach sections may be arranged as illustrated in a modified ferm of breach, as shown in Figs. '4 to 6. This form is generally similar te the ferm of Figs. 1 te 3, and like parts are therefore identified by the same reference numerals plus the letter a.

' The supportV la is'form'ed with two longitudinally inclined grooves 2lia and 2Ia which are spaced further apart than the grooves 2i) and 2| o f Fig. 2, but which in every other respect cerrespond te the latter.

Two series of breach sections 8a are removably secured by means of bolts 2li.a against the eppesitely inclinedmounting surfaces 23a.

Za v and 2Ia will cut from opposite side edges toward the center ef the werk surface Si along the cutting planerl'la. l

Mounted in a vertical rectangular groeve 28 in the leading end o f Vthe support Ia between the leading pair of opposed breach sections 8a is an upright breach section 29 extending parallel te the path of movement. The tep of the breach section 29 is formed with a longitudinall series of breach teeth 3i) of progressively increasing cutting amplitude from the leading tewardthe trailing end so as te ferm a longitudinal starting groeveV 32 in the intermediate portion of the work surface Si. The section 29 may be the same in form as the sections 8a, but .withthe trailing end elevated to provide the progressive cutting amplitude.

Also formed in the support "la, intermediatethe grooves 20a and 2l1 and Vtrailing the groeve; 2 8, is an inclined groove 33 similar Vin form and parallel to the trailing portion of the groevegZla, A series of breach sections 8a are removably mounted in the groove 33, and in eperatien act te cut from the groeve 32 formed by the breach section 29 across the work surface Si outwardly toward the groove 20%. Y The last trailing sections 8a in the greevesZIa and 33 respectively overlap the cutting rangeof the breach section 28 and the trailing breach section 8a in the groeve Zilase that the surface Si is completely traversed in the breaching operation. In the continued movement of the s upport la, the breach section 25a is adapted te cut the surface S1 te the final depth and finish.

I claim as my'inventien: v

l. A surface breach comprising, in combination, a rectilinearly movable support, an'elongated breach section removably mounted on 'Said support and having a longitudinal series of transverse teeth of uniform height and width extending completely across the body of said section and charnfered at opposite ends te provide eppesitely inclinedslide cutting edges and intermef diate top cutting edges, and meansy fersecuring said section te said support in a longitudinally inclined yposition and laterally tilted at the angle of said side cutting edges to present one seter the other of said side cutting edges of said series of teeth to the Work. Y Y- 2. A surface breachV comprising, in combination, a rectilinearly movable'suppert, an elengated breach section removably mounted on said support and having a longitudinal series of transverse teeth extending across the body ofsaidsectien and chamfered at opposite ends te provide oppositely inclined side cutting edges, and means for securing said section tersaid suppertwith the It will be evident that the two series Vof rbreach sections thus mounted in the grooves successive teeth disposed in offset relation longitudinally of said support, and tilted laterally at the angle of, said cutting edges so as to dispose selectively one series or the otherof said side cutting edges uppermost in cutting position.

, 3. A symmetrical surface broach sec-tion comprising a longitudinal bar of rectangular transverse form having fiat parallel sides and a flat perpendicular bottom surface,r and formed along the top with a single longitudinal series of relieved transverse 'broach teeth of uniform height, width and cutting contour extending laterally across the top of said bar in parallel relation to said bottom surface, the longitudinal axis of symmetry of said series of teeth being parallel to said sides, the ends of said teeth being symmetrically chamfered to provide inclined side cutting edges of equal but opposite degree and intermediate top cutting edges.

4. A surface broach comprising, in combination, a rectilinearly movable support having laterally spaced mounting surfaces oppositely inclined both laterally and longitudinally, and a plurality of elongated broach sections removably mounted on said surfaces and having on the top a longitudinal series of relieved teeth of uniform height and Width, said broach teeth having a symmetrical cutting contour with cutting edges along the sides of each section oppositely inclined to the tops at the angle of said mounting surfaces, and means for securing said sections intercnhangeably to said support.

5. A surface broach comprising, in combination, a rectilinearly movable support, a pair of opposed ,broach sections removably secured in laterally spaced relation to said support, said sections being oppositely inclined longitudinally of the direction of movement to converge symmetrically toward each other from the trailing toward the leading end, and being alike in form, each broach section having a longitudinal series of teeth of uniform height and Width and with oppositely inclined side cutting edges, and means for securing said sections removably hand interchangeably vto said support, said sections being laterally inclined toward each other to `present the outermost side cutting edges uppermost in position respectively t cut from vthe outer edges of a Work surface toward the center thereof, whereby interchanging said sections in position on said support Will interchange the location in cutting position of the side cutting edges of each section.

6. A surface broach comprising, in combination, a rectilinearly movable support formed with grooves converging longitudinally toward each other from the leading to the trailing end, and having inclined mounting surfaces of equal but opposite degree relative to the plane of cut, a series of like broach sections removably secured in end to end relation Within said grooves, each section having a longitudinal series of'teeth of uniform height and width and with oppositely inclined side cutting edges, and means for securing said broach sections interchangeably against said mounting surfaces, whereby rst one series and then the other series of said side cutting edges of each section may be located in cutting position.

7. A surface broach comprising, in combination, a movable support formed in the top With a longitudinally inclined V-groove having a backing surface and a clamping surface arranged at right angles to each other, an elongated broach section having a bottom surface adapted to engage said backing surface and a sidesurface adapted to be. positioned against said clamping surface, said broach section having on the top a single longitudinalf series of relieved teeth with oppositely inclined symmetrical cutting edges along opposite sides and intermediate cutting edges along the top, said groove being laterally orientated so that one seriesv of side cutting edges Will be disposed uppermost in cutting position.

8. A surface broach comprising, in combina.- tion, a rectilinearly movable support formed with a pair of laterally spaced longitudinally inclined mounting grooves converged toward each other from the leading toward the trailing end, each of said grooves being right angled in transverse form to present a backing surface and a clamping surface, the .clamping surfaces of said grooves being laterally inclined toward each other at the same but opposite degree, an'elongated broach section adapted to be selectively mounted in either of said grooves, said section being rectangular in transverse form and having a bottom surface adapted to seat against said backing surface and having parallel side surfaces adapted selectively to seat against said clamping surface of the selected groove, said section being formed with a longitudinal series of broach teeth of uniform height and cutting conto-ur with oppositely inclined cutting edges along opposite sides, and means for removably securing said broach section selectively against the clamping surface of either of said grooves, whereby one or the other of said series of inclined cutting edges may be disposed in cutting position to cut from either side of the Work.

9. A surface broach comprising, in combination, a rectilinearly movable support formed with a pair of laterally spaced longitudinally inclined mounting grooves converged toward each other from the leading toward the trailing end, each of said grooves being right-angled in transverse form to present a backing surface and a clamping surface, the clamping surfaces of said grooves being laterally inclined toward each other at the same but opposite degree, a plurality of elongated broach sections adapted to be selectively mounted in said grooves, each section having a bottom surface adapted to seat against the backing surface and parallel side surfaces adapted selectively to seat against the clamping surface of the selected groove, and being formed with a longitudinal series of broach teeth with oppositely inclined cutting edges along opposite sides, and means for removably securing said broach sections selectively and interchangeably against the clamping surfaces of said grooves, whereby one or the other of said series of cutting edges of each section may be disposed in cutting position.

10. A surface broach comprising, in combination, a rectilinearly movable support, a plurality of broach sections removably and interchangeably secured in laterally opposed and series relation on said support, and each being formed with a longitudinal series of broach teeth, certain of said sections being inclined laterally and longitudinally of the line of cut and converging in series from the leading toward the trailing end tocut from opposite sides toward the center of the Work surface, and an intermediate series of broach sections mounted on said support, the leading section of said intermediate series extending parallel to the line of cut to form a starting groove, and the trailing section of said intermediate series being spaced from and parallel to one of the outermost series of broach sections to `cut.latera1ly across the Work surface from said 10 tions.

section and adapted to cut from one side`V toward the' center of the Work surface, trailingbroach sections secured in laterally spaced relationl-to said support inseries respectively with said first mentioned sections, and converging towardeach other from the leading toward the trailing end, and a longitudinally inclined broach section secured to said support and arranged to'cut across the terminal area left by said last mentioned Ysec- JOI-IN A. MARKSTRUM. 

